1. Field of the Invention
The present invention relates to an inductive-type thin-film magnetic head and a magnetic storage apparatus using the magnetic head.
2. Description of the Prior Art
Recently, the recording density of a hard disk drive has been remarkably improved. A recording density after 1990 tends to rise at an annual rate of approx. 60%. To improve the recording density of a hard disk drive, it is preferable to improve the recording track density by decreasing the track width of a magnetic head. Moreover, to improve the recording density, improvement of the recording bit density is similarly important. To improve the recording bit density it is preferable to increase the resistance to applied magnetic force (Hc) of a magnetic storage medium. Moreover, to write data in a magnetic storage medium having a high Hc, it is preferable to use an inductive recording head having a high recording capacity. Furthermore, to efficiently detect a signal from micro-scaled recording bits, it is preferable to use an MR reproducing head. Therefore, an MR-inductive composite-type thin-film magnetic head obtained by combining an MR reproducing head with an inductive recording head is prospective for high-density recording.
FIG. 19 is a sectional view of a conventional thin-film magnetic head. The conventional thin-film magnetic head will be hereafter described by referring to FIG. 19.
A conventional thin-film magnetic head 70 is constituted by laminating a lower shielding layer 74, a read gap layer 80 holding an MR magnetosensitive element 78 in an ABS plane 76, a common pole layer 82 serving as an upper shielding layer and a lower pole layer, and a write gap layer 84 in order on an insulating substrate 72, then laminating a first flattening layer 86, a coil pattern layer 88, and a second flattening layer 90 in order on the write gap layer 84 excluding the vicinity of the ABS plane 76, and by laminating an upper pole layer 92 on the write gap layer 84, first flattening layer 86, and second flattening 90 nearby the ABS plane 76.
The common pole layer 82 serves as an upper shielding layer for improving the reproducing resolution of an MR reproducing head and a lower pole layer of an inductive recording head. The MR magnetosensitive element 78 detects a signal magnetic field from a not-illustrated magnetic storage medium facing the ABS plane 76. The thickness of the write gap layer 84 serves as the gap of the inductive recording head. The first flattening layer 86 serves as the insulating base of the coil pattern layer 88 and the second flattening layer 90 corrects the irregular height difference in the coil pattern layer 88. The portion free from the first flattening layer 86 on the write gap layer 84 nearby the ABS plane 76 specifies the gap depth D of the inductive recording head. The recording track width is determined by the front end portion width W (not illustrated) of the upper pole layer 92. The front end portion width W represents the width of the upper pole layer 92 on the ABS plane (front end) in the direction vertical to a drawing surface, which is illustrated in FIG. 2 and the like.
To improve the recording capacity under high-density recording, it is preferable to decrease the gap depth D to 1 μm or less. Moreover, to correspond to high-density recording, it is preferable to realize the upper pole layer 92 having a minimum front end portion width W.
Furthermore, an invention for improving the recording density is disclosed in the official gazette of Japanese Patent Application Laid-Open No. 9-305930. This invention attains its object by using a magnetic recording/reproducing head configured by superimposing a sealed-type MR head on an inductive-type magnetic recording head and thereby, improving the accuracy of widths of the recording coil and recording track of an upper recording head.